you are right nadeem khan but when ever i refill my tank after warning light the max is 38-40 ltrs,so i guess reserve is of 6-7ltrs, never took the risk to empty the whole tank .
some petrol pumps have wrong scales to fool us.

from 0 to very first solid white bar on fuel guage, i think every corolla (old shape) variant requires 6 litres and when I experienced 55 litres at that time my car's fuel guage was even two step above that solid bar point , roughly it meant 6+2.5+2.5= 11 LItres.....

Even at that very point I was having 10-12 litres of fuel and upto aforesaid point my car accomodated 45 litres in its fuel tank , making the whole figure as 55 app.. Bhaiyya it depends on filling style too and as i clarified I fill its belly up till fuel stays at fuel inlet point, no disappearing after giving it a few shakes or a few miles drive